Algebraic Properties of Qualitative Spatio-Temporal Calculi

Qualitative spatial and temporal reasoning is based on so-called qualitative calculi. Algebraic properties of these calculi have several implications on reasoning algorithms. But what exactly is a qualitative calculus? And to which extent do the qualitative calculi proposed meet these demands? The literature provides various answers to the first question but only few facts about the second. In this paper we identify the minimal requirements to binary spatio-temporal calculi and we discuss the relevance of the according axioms for representation and reasoning. We also analyze existing qualitative calculi and provide a classification involving different notions of a relation algebra.Comment: COSIT 2013 paper including supplementary materia

Chaotic, memory and cooling rate effects in spin glasses: Is the Edwards-Anderson model a good spin glass?

We investigate chaotic, memory and cooling rate effects in the three dimensional Edwards-Anderson model by doing thermoremanent (TRM) and AC susceptibility numerical experiments and making a detailed comparison with laboratory experiments on spin glasses. In contrast to the experiments, the Edwards-Anderson model does not show any trace of re-initialization processes in temperature change experiments (TRM or AC). A detailed comparison with AC relaxation experiments in the presence of DC magnetic field or coupling distribution perturbations reveals that the absence of chaotic effects in the Edwards-Anderson model is a consequence of the presence of strong cooling rate effects. We discuss possible solutions to this discrepancy, in particular the smallness of the time scales reached in numerical experiments, but we also question the validity of the Edwards-Anderson model to reproduce the experimental results.Comment: 17 pages, 10 figures. The original version of the paper has been split in two parts. The second part is now available as cond-mat/010224

Social Inequalities of Post-secondary Educational Aspirations : influence of social background, school composition and institutional context

The first goal of this article is to assess, for each country belonging to the Organisation for Economic Co-operation and Development (OECD), the influence of pupils’ sociocultural background on educational aspirations. The second goal is to explore whether, after controlling for educational achievement, the residual influence of sociocultural background is still significant. In addition, the author estimates whether the sociocultural and academic characteristics of school composition have an additional impact on educational aspirations in this group of countries. Finally, they shows that the structural characteristics of school systems moderate the influence of individual characteristics and school composition on educational aspirations

Gender inequalities in higher education: extent, development and mechanisms of gender differences in enrolment and field of study choice

In the course of educational expansion, ‘gender differences in access to higher education have decreased substantially in many European countries. In Germany women are currently over-represented in upper secondary education and more frequently attain a general qu1alification for university entrance. Despite those advantages, women still enrol in higher education less frequently. Even where they apply to higher education, their field of study choices differ from those of men. Drawing on recent data on upper secondary graduates, we seek to understand which factors account for both phenomena. Our findings suggest that the growing gender gap in the transition to higher education can be largely ascribed to differential perceptions of labour market outcomes. In addition, the more risk-averse assessment of study costs and success probabilities are more important for women's decision not to enter higher education. Furthermore, the gender gap in the choice of a technical field can be explained by differences in the subjectively perceived comparative advantage in technical skills and by differences in educational motivations and conceptions of life and career plans. These results lead to the conclusion that gendered educational choices are the consequence of effects that have their provenance much earlier in life